Developers, IT pros won't get the update early, as they have historically

Microsoft today declared Windows 8.1 ready for computer and tablet makers, saying the update had reached its RTM, or "release to manufacturing" milestone.

Seven weeks ago, Microsoft executive Tami Reller, then the chief financial officer of the Windows division but now its head of marketing, promised that Windows 8.1 would go out to OEMs, computer- and tablet-making partners, in late August.

Microsoft already revealed the public release date for Windows 8.1 as Oct. 17 in the U.S., when current Windows 8 users will be able to download and install the operating system's second version. Windows 8.1-powered devices, and the update itself, will hit retail stores on Oct. 18.

Unlike previous editions of Windows, which have made do with bug collection updates called "service packs," Microsoft has added numerous new features and functions to Windows with 8.1, some devoted to making the OS more palatable on conventional desktop and notebook PCs, and many aimed at businesses, which have largely ignored Windows 8.

RTM is largely meaningless to end users; it simply marks the date when OEMs (original equipment manufacturers) receive the code and can begin testing it on new devices. The fact that it met its deadline, however, signals that new devices powered by Windows 8.1 will be available by the time the holiday selling season starts to warm up.

In fact, RTM no longer represents finished code, at least by Microsoft's standards.

"While our partners are preparing these exciting new devices we will continue to work closely with them as we put the finishing touches on Windows 8.1 to ensure a quality experience at general availability on October 18," said Antoine Leblond, a Microsoft spokesman, in a blog.

Microsoft also cleared up the mystery whether developers and IT professionals would have early access to Windows 8.1, or must wait until October like everyone else. Previously, the company refused to say one way or the other.

"In the past, the release to manufacturing (RTM) milestone traditionally meant that the software was ready for broader customer use," Leblond said. "However, it's clear that times have changed."

MSDN (Microsoft Developer Network) and TechNet subscribers will not, as they have historically, have access to Windows 8.1 several weeks before the general public, Microsoft ruled. TechNet is a service aimed at IT professionals, while MSDN courts developers.

The early availability of finished code to developers and enterprise IT personnel allowed those groups to get an early jump on final testing of their applications and more time to evaluate the OS before deciding whether to bring it into their companies.

The possibility that MSDN subscribers would not get their hands on Windows 8.1 early raised hackles when reports first claimed developers would have to wait. Wes Miller, an analyst at Directions on Microsoft, had said Microsoft was wrong not to support developers in every way possible, given the importance of their apps to the success of Windows 8.1. "That would be a mistake," said Miller in a interview two weeks ago. "They have to get it out there as soon as possible."

Microsoft hopes that Windows 8.1 sparks more interest in the radical operating system than customers have shown so far. Although Windows 8 accounted for 6% of all copies of Windows used last month, that was about a third the share captured by Windows 7 at the same point in its post-release timeline.

Windows 8 has also been hampered by a dramatic slowdown in PC shipments and lackluster sales of tablets armed with the OS. The Windows 8.1 update could boost tablet sales, as it allows for devices with smaller screens, the category that has sold best so far this year.